God I am such a wuss at times. Tinkerbell appears to have moved into the corridor - i.e. the fire alarm is peeping which I guess means the battery needs changing. Supposedly it's a simple case of inserting a screwdriver into a slot and then 'pushing the case away'. So after about 15 minutes of swinging off the ceiling on the end of a screwdriver I still haven't got the case off. Bah. I'm going to have a cup of tea and then retry, and then I'm leaving it until the father comes down next week. Why is there never a sonic screwdriver around when you need one?